New gene discovery - (Jan/16/2013 )

Hello all,

I need to find (theoretically) a new gene about a disease which has no etiological knowledge for my homework.
Can I use something like RFLP if I have no knowledge about it?
I don't know how to start without any information about a particular gene. Should I theoretically look for a population and sequence DNAs of a control group and diseased group? What should be my approach to start?

Thanks.

But I need to add, I don't know where to look for this mutation in the whole genome. How can I have more information about where to look?